As a film formation method, for example, there has been known a method for forming a film by supplying a film-forming ink obtained by dissolving a film-forming material in a solvent onto a base material using a liquid droplet ejection method, and removing the solvent from the film-forming ink on the base material (see, for example, PTL 1).
It has been proposed that by using this film formation method, for example, an organic layer (for example, a light-emitting layer, a hole transport layer, etc.) of an organic electroluminescence (organic EL) element, a colored layer of a color filter, a conductor pattern of a wiring board, etc. are formed.
Patterning (film formation method) of such an organic layer or a film of a conductor pattern or the like is performed by forming a partition wall (bank) including an opening part corresponding to the shape of a film to be formed to ensure a film-forming region, and then, supplying a film-forming ink as a liquid droplet into the opening part, and thereafter removing a solvent by heating.
That is, in a film formation method for a film having such a configuration, generally, a film-forming ink (liquid droplet) is supplied into an opening part included in a partition wall whose surface has been subjected to a water repellency treatment, and thereafter, a solvent is removed by natural drying or by heating through vacuum drying or the like, whereby a film is formed.
At this time, due to a coffee stain phenomenon, a film is formed into a shape in which a film thickness in a central portion is thin and a film thickness at a partition wall edge is thick, that is, the vertical cross-sectional shape is U-shape.
Here, a film whose vertical cross sectional shape is a U-shape is formed by the occurrence of “seeping-up” such that the film-forming material seeps up on a partition wall surface of the partition wall when the solvent is removed by heating. Therefore, due to the occurrence of this “seeping-up”, a problem that it becomes difficult to form a film having a uniform thickness arises.
In order to solve such a problem, for example, PTL 2 has proposed that an application step of supplying a liquid droplet into an opening part and a drying step of drying the liquid droplet are performed in a state where a substrate is placed on the same stage, therefore, transfer between the respective steps is performed promptly so as to suppress “seeping-up” of the film-forming material, thereby forming a uniform film. Incidentally, PTL 2 has also proposed that a more uniform film is formed by repeatedly performing these application step and drying step a plurality of times.
However, by such a method, “seeping-up” caused by natural drying of an ink for which the drying time is relatively long can be suppressed, however, “seeping-up” caused by vacuum drying for which the drying time is short cannot be effectively suppressed, and also the method has a problem that huge cost is required for production of a device realizing this method.